Since the latest patch, I've played two Egyptian campaigns where NPCs won't fill open court positions. Once they've died or are otherwise forced to vacate their position, no other factions try to fill the open positions. I even tried trading large sums of gold to factions with the highest amount of Legitimacy (as indicated by the UI when you hover over the court positions, as to who may potentially fill the spot), and this didn't seem to trigger them to join it (assuming NPCs even have to spend gold to join the court?)

I haven't played any of the other factions, so I'm unsure if this is just an issue with the Egyptian court or other courts as well.